The present invention concerns the stabilization of hydrogen peroxide in acidic aqueous compositions containing metallic ions. The acid or acids present in such compositions can be partially in the form of salts.
Such solutions find application particularly in the surface treatment of metals, like scouring, polishing and chemical attack of stainless steels or of copper, or in the manufacture of hydrated uranium peroxide.
These solutions are unstable both during their employment and while at rest, with the metallic ions which they contain catalyzing the decomposition of the hydrogen peroxide.
Remedies have been proposed in order to reduce the rate of this decomposition of the hydrogen peroxide in solutions of the same type, but have not been entirely successful.
For instance, British Pat. No. 1,164,347 proposes the addition of one or more saturated aliphatic alcohols to an aqueous solution of hydrogen peroxide containing hydrofluoric acid, used for the chemical polishing of copper and its alloys.
U.S. Pat. No. 3,537,926 recommends the addition of a carboxylic or dicarboxylic aromatic acid, such as benzoic acid, to acidic aqueous solutions containing hydrogen peroxide and ammonium bifluoride (HF, NH.sub.4 F) used for the polishing of iron alloys.
The Japanese patent application, Japan Kokai No. 73 52638 claims the addition of urea and an inorganic acid to aqueous solutions of hydrogen peroxide containing hydrofluoric acid or its salts, used for the polishing of iron and steels.
French patent application No. 81 17757 published under number 2,513,258 recommends the use of 3-amino-1,2,4-triazole in order to stabilize aqueous solutions of hydrogen peroxide containing metallic ions and one or more acids if necessary, such as sulfuric acid and phosphoric acid.
The remedies stated above in order to improve the stability of such solutions present the drawback of still being insufficiently efficacious and/or having harmful consequences for the environment.